It protects a 1P+N circuit at 230/240 V AC, 50 Hz, with a rated current of 20 A at 30 °C ambient — derated to 14.6 A at 70 °C. The Type AC residual current detection handles sinusoidal AC earth faults — the common domestic and light commercial waveform. The instantaneous design means no intentional time delay on the RCD element; it trips within the standard 40 ms window for a residual current at or above the rated sensitivity.
The 5SU1454-1KK20 occupies 2 modular width units (36 mm) on a DIN rail, with a depth of 77 mm and an installation depth of 70 mm. It mounts in any position — no derating for orientation — and accepts supply from either top or bottom. The IP20 rating applies once the distribution board is installed with connected conductors; the enclosure itself provides basic finger protection but expects to live inside a closed panel.
The 20 A rating at 30 °C is the headline number; the real-world capacity depends on your panel's internal temperature. At 40 °C it carries 18.8 A, at 55 °C it drops to 16.2 A, and at 70 °C the continuous current is 14.6 A. If your distribution board runs hot — say, tightly packed with other breakers or in a warm cabinet — size the load accordingly. The 1P+N configuration (one protected pole, one switched neutral) is standard for single-phase final circuits.